H.B. Fuller

H.B. Fuller – Edgebanding adhesives

Deciding the right adhesive for your application: What is the difference between EVA and PO, HMMC (PUR) hot melt adhesive?

Hot melt adhesives are used for bonding solid wood, aluminium, veneer, melamine, polyester, HPL, PVC, ABS, PP edgings of various thickness to core boards. EVA hot melt adhesives are based on Ethyl-Vinyl Acetate (EVA) , while Polyolefin hot melt adhesives are based on Polyolefin (PO) and HMMC (PUR) hot melt adhesives are based on polyurethane (PUR). Edgebanding using EVA hot melt is commonly used due to ease of use, but HMMC (PUR) is gaining ground rapidly with exceptional benefits. If joints need to be water or heat resistant (fire doors) then HMMC (PUR) adhesive Rakoll® PUS 550 T is recommended as this has a significantly higher water and heat resistance than an EVA adhesive.

HMMC = Hot Melt Moisture Cure (PUR)

Polyolefin based formulation of Rakoll® 5728 for edgebanding applications has better hydrolysis and heat resistance than EVA based adhesives. It is easier to apply than HMMC (PUR) adhesives and also lowers the formation of strings at the application unit, whilst providing better stability in the melting equipment, in comparison with standard EVA based adhesives.

PUR based adhesives will always outperform EVA or PO adhesives !

EVA hot melt adhesives are classed as filled and unfilled adhesive. Filled glue Rakoll® K 4/581, are generally lower costing and in addition to the adhesive resins, contain fillers such as chalk, which can at low speeds help prevent stringing. Unfilled hot melt adhesives Rakoll® Supermelt Plus can be applied thinner to give a tighter joint, offer high glue mileage and high final bond strength. Products like Rakoll® Supermelt Professional are 10% filled and offer unfilled performance without stringing !

Note: When using HMMC (PUR) based adhesives chemical cross-linking is achieved within few days. However it is important that the bonded materials are stored above 15c for full cure to take place. Under 15c and the curing process is stalled !

Are PUR adhesive easy to use ?

In a nutshell, yes, with care ! With HMMC (PUR) Hot melt you can achieve a thinner glue line, high final bond strength, produces tight joints, excellent heat and water resistance and clean running

Note: not all edgebanders are equipped to run HMMC (PUR) adhesives, (always check with your machine supplier to suitability). What is very important when using HMMC (PUR) adhesives is purging of the adhesive melt tank and applicator (nozzle/roller) after use with a suitable cleaning agent – Ipatherm 13 HMMC (PUR) Cleaner. HMMC (PUR) adhesives once cured, unlike EVA adhesive, will not re-melt !!!! Good house-keeping is required at all times.